CAIRO — The association of judges in Cairo called Saturday for courts across Egypt to suspend all but their most vital activities to protest an edict by President Mohammed Morsi granting himself unchecked power by setting his decrees above judicial review until the ratification of a new constitution.

The judges’ strike, which drew the support of the leader of the national lawyers’ association, would be the steepest escalation yet in a political struggle between the country’s new Islamist leaders and the institutions of the authoritarian government that was overthrown last year. As it spills into the courts and the streets, the dispute also increasingly threatens to undermine the credibility of Egypt’s political transition as well.

A council that oversees the judiciary denounced Morsi’s decree, which was issued Thursday, as “an unprecedented attack on judicial independence,” and urged the president to retract parts of the decree eliminating judicial oversight.

State news media reported that judges and prosecutors had already walked out in Alexandria, and there were other news reports of walkouts in Qulubiya and Beheira, but those could not be confirmed.

Outside Egypt’s high court in Cairo, police fired tear gas at protesters who were denouncing Morsi and trying to force their way into the building, the second day in a row that protesters took to the streets over the presidential decree, which critics have decried as a return to autocracy.

Abdel Meguid Mahmoud, a prosecutor appointed by Morsi’s predecessor, Hosni Mubarak, declared to a crowd of cheering judges that the presidential decree was “null and void.”

He denounced what he described as “the systematic campaign against the country’s institutions in general and the judiciary in particular.”

A coalition of disparate opposition leaders including the liberal former U.N. diplomat Mohamed ElBaradei, the leftist-nationalist Hamdeen Sabahy, and the former Mubarak-government foreign minister Amr Moussa formed a self-proclaimed National Salvation Front to oppose the decree.

In addition to demanding the dissolution of the constitutional assembly, the group declared that it would not speak with Morsi until he withdrew his decree.

“We will not enter into a dialogue about anything while this constitutional declaration remains intact and in force,” Moussa said. “We demand that it be withdrawn and then we can talk.”

Advisers to Morsi, a former leader of the Muslim Brotherhood and Egypt’s first democratically elected president, defended his action, saying he was trying to prevent the courts from disbanding the Islamist-dominated constitutional assembly, which is writing a new constitution.

The advisers said a court decision on the new constitutional assembly had been expected as soon as next Sunday.

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